The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.
Pure mullite has a melting point (and decomposition temperature) of ˜1850° C. and as such, mullite often is used as a refractory material. In practice, however, commercial mullite refractory products always contain glass as a residual product of the raw materials and processing. The glass component typically resides between the mullite grains and assists in bonding the grains together. Accordingly, as the glass softens (at ˜1200° C.), the mullite refractory material begins to deform by viscous flow when heated at or above this temperature (approximating the glass transition temperature). In seeking to address the issue of glass softening, conventional approaches to the formation of mullite tend to focus on the minimisation of the glass-forming components and fluxes in the starting material for commercial mullite formation.